In an intriguing development, Towerstream has announced that it is beta testing mobile VoIP over WiFi in Rhode Island.  Quote:

Today TowerStream announced the successful completion of Mobile Voice over IP (VoIP) over a WiFi network.  The one-month trial, conducted in Middletown, Rhode Island, leveraged TowerStream’s existing pre-WiMAX network enabling VoIP phone calls to pass seamlessly between WiFi access points without dropping the call.

Consumers in New York City will soon be able to sign up for a free Beta trial of the service at http://www.towerstream.com/voip.  Beta users will be able to log onto the website to get up-to-date information as to where the service is available.  Users with any VoIP WiFi-enabled device or notebook will be able to utilize TowerStream’s network for free and make phone calls.

Via VoIP Watch.